Illustration of (A) spatial and (B) temporal smoothing of a contour created by the points in the middle of the region of interest (ROI), as shown in Figure
A. To obtain a regularly moving ROI throughout the heart cycle, the smoothing procedure restricts the ROI from large or irregular movements from frame to frame. In (A), increasing the spatial smoothing will, for each separate frame of the heart cycle, reduce kinks or steps in the contour. With smooth contours at each frame, increasing the temporal smoothing will, on the other hand, enable a smooth transition between contours from frame to frame, as indicated in the rightmost column of (B). Arrows indicate increasing degree of smoothing.